/// <summary>
/// EF works with transactions by default - calling SaveChanges() starts a transaction by default.
/// However we can use transactions to unify many calling of SaveChanges() as one and if one fails - all fail.
/// </summary>
public static void Main()
{
using (var db = new NorthwindEntities())
{
using (var transaction = db.Database.BeginTransaction())
{
var order = new Order()
{
CustomerID = "WELLI",
EmployeeID = 4
};
db.Orders.Add(order);
var orderDetails1 = new Order_Detail()
{
OrderID = order.OrderID,
ProductID = 5,
UnitPrice = 12.34m,
Quantity = 100,
Discount = 0.2f
};
var orderDetails2 = new Order_Detail()
{
OrderID = order.OrderID,
ProductID = 3,
UnitPrice = 12.34m,
Quantity = 100,
Discount = 0.2f
};
var orderDetails3 = new Order_Detail()
{
OrderID = order.OrderID,
ProductID = 4,
UnitPrice = 12.34m,
Quantity = 100,
Discount = 0.2f
};
db.Order_Details.AddRange(new[] { orderDetails1, orderDetails2, orderDetails3 });
try
{
db.SaveChanges();
}
catch (System.Exception ex)
{
System.Console.WriteLine(ex);
transaction.Rollback();
}
transaction.Commit();
}
}
}
{ // TODO: Create a method that places a new order in the Northwind database.
// The order should contain several order items.
// Use transaction to ensure the data consistency.
static void Main()
{
Order newOrder = new Order();
newOrder.OrderDate = DateTime.Now;
newOrder.RequiredDate = DateTime.Now + new TimeSpan(3, 0, 0, 0); //thre days later
newOrder.ShipCountry = "Bulgaria";
newOrder.ShipCity = "Burgas";
int numberOfRepeatsUntilSuccess = 3;
try
{
CreateOrder(newOrder, numberOfRepeatsUntilSuccess);
}
catch (InvalidOperationException ex)
{
Console.WriteLine("{0} \n{1}", ex.Message, ex.InnerException.Message);
}
}
private static void CreateOrder(Order newOrder, int numberOfRepeatsUntillSuccess)
{
bool isTransactionSucceed = false;
using (NorthwindEntities dbContext = new NorthwindEntities())
{
using (TransactionScope transaction = new TransactionScope())
{
for (int i = 0; i < numberOfRepeatsUntillSuccess; i++)
{
try
{
dbContext.Orders.Add(newOrder);
dbContext.SaveChanges();
transaction.Complete();
isTransactionSucceed = true;
break;
}
catch (UpdateException ex)
{
if (i == numberOfRepeatsUntillSuccess - 1)
{
throw new InvalidOperationException("Cannot complete order creation", ex);
}
}
}
if (isTransactionSucceed)
{
// Reset the context since the operation succeeded.
Console.WriteLine("Transaction sompited");
}
else
{
Console.WriteLine("The operation could not be completed in "
+ numberOfRepeatsUntillSuccess + " tries.");
}
}
}
}
private bool FilterOrders(Order entity)
{
return (entity.CustomerID == this.CustomerID);
}
private bool FilterOrder(Order entity)
{
return (entity.OrderID == this.OrderID);
}
private void DetachOrders(Order entity)
{
entity.Customer = null;
}
private void AttachOrders(Order entity)
{
entity.Customer = this;
}
/// <summary>
/// Create a new Order object.
/// </summary>
/// <param name="orderID">Initial value of the OrderID property.</param>
public static Order CreateOrder(global::System.Int32 orderID)
{
Order order = new Order();
order.OrderID = orderID;
return order;
}
/// <summary>
/// Deprecated Method for adding a new object to the Orders EntitySet. Consider using the .Add method of the associated ObjectSet<T> property instead.
/// </summary>
public void AddToOrders(Order order)
{
base.AddObject("Orders", order);
}
public static void AddOrder(NorthwindEntities northwind, Order order)
{
northwind.Orders.Add(order);
northwind.SaveChanges();
}
